Bifurcation and stability of forced convection in tightly coiled ducts: stability

A numerical study is made on the stability of multiple steady flows and heat transfer in tightly coiled ducts by examining their responses to finite random disturbances. It is found that possible physically realizable fully developed flows evolve, as the Dean number increases, from a stable steady symmetric 2-cell flow at lower Dean numbers to a temporal periodic oscillation, a temporal intermittent oscillation, another temporal periodic oscillation, the co-existence of stable steady symmetric 2-cell flow and temporal oscillating flows (either periodic or aperiodic), and the co-existence of three stable steady 2-cell flows (either symmetric or asymmetric) and aperiodic oscillating flows. (c) 2005 Elsevier Ltd. All rights reserved.